This invention relates generally to hydraulic nonmechanical pumping devices for transferring material, and specifically, to jet pumps for moving solid, semi-solid and/or liquid materials, as well as methods which employ such devices.
Numerous types of pumps have been developed for moving matter from one location to another. Typically, the physical and/or chemical nature of the material being moved by the pump plays an important role in pump efficacy. For example, the dredging industry commonly utilizes large centrifugal pumps for suction and movement of slurry material, i.e., water or other liquid in admixture with solid particulate matter, e.g., sand or gravel. Because of the abrasive characteristics of particles within such slurry material, these pumps typically suffer wear and tear and significant downtime to repair equipment components, especially moving parts which come into direct contact with the particulate matter.
Another dredging technique involves the use of air to induce an upward flow of water. This technique has typically involved compressed air or gas, requiring expensive compression equipment. In addition, the combination of gas, water and solids has contributed to process instability in the mixing chamber of the device, as discussed in U.S. Pat. No. 4,681,372.
Other hydraulic pumps employed in dredging and deep sea mining operations employ jet eduction systems, in which water is forced through piping configurations to cause an upward flow that pulls the water and solid material from the desired location. However, many jet eductor systems are flawed in that their high pressure water jets, while effective at removing high volumes of slurry material, cause severe cavitation in the throat and mixing regions of the eductor conduit, and result in lowered efficiency and extremely short equipment life, as discussed in, e.g., U.S. Pat. No. 4,165,571.
Other jet eduction systems have used atmospheric air for the purpose of creating air bubbles for separation processes, as in U.S. Pat. No. 5,811,013. These systems are not designed to increase pump efficiency, prevent pump cavitation or increase pump flow as disclosed by the present invention. However, U.S. Pat. No. 5,993,167 does disclose a jet eduction system which permits air to form a layer surrounding a high pressure flow of liquid, which is directed through a space and into a tube, thereby forming a vacuum in the space. Yet, this system does not produce vacuum sufficient for many commercial operations, and does not provide for control of the weight percentage of solids in pumped slurries.
Thus a need continues to exist for a commercially viable jet eduction system which moves large volumes of matter with very little wear and tear on the system. A need also exists for systems which enabling users to achieve greater pumping efficiency.
The present invention overcomes the shortcoming of prior developments by providing, among other things, a pumping system which can (a) increase the quantity of material moved, relative to previously developed pumps, without an increase in energy consumption, (b) move solid materials with minimal wear on component parts, (c) overcome the problems associated with traditional venturi effect pumps, (d) include specific component parts which are designed to wear and which can be easily changed, (e) produce a vacuum for suctioning material with little or no cavitation, and/or (f) enable the control of the solid to liquid ratio of the material being pumped to drastically increase the pumping efficiency. Moreover, the present invention provides an efficient mixing system which employs a jet pump of this invention and enables users to rapidly form a liquid and solid material mixture, preferably one in which the mixture is substantially homogeneous, to control the weight percent of solids in the resulting mixture, and to efficiently transport the mixture downstream from the jet pump to a desired location.
Thus, in one embodiment of the present invention, an improved liquid jet pump is provided. The liquid jet pump is comprised of a nozzle assembly that pulls in atmospheric air. The liquid jet created by passage of liquid through the nozzle assembly has minimal deflection as it exits because of an atmospheric air bearing surrounding the liquid jet. Consequently, the liquid jet pump has improved efficiency and capacity. The liquid jet pump is configured to define a suction chamber and further comprises a suction pipe. The suction pipe pulls in the material to be pumped as the liquid jet from the nozzle assembly passes through the suction chamber. The liquid jet pump further comprises a target tube that receives the liquid jet combined with material to be pumped which enters the suction chamber after traveling through the suction pipe. The target tube is comprised of a housing support detachable from the suction chamber and a wear plate of abrasion-resistant material.
In another embodiment, this invention provides apparatus which is comprised of(a) a nozzle assembly which is sized and configured to (i) receive a pressurized liquid and a gas, and (ii) eject the pressurized liquid as a liquid flow while feeding the gas into proximity with the periphery of the liquid flow; (b) a housing defining a suction chamber into which the nozzle assembly may eject the liquid flow, the housing also defining a suction inlet and a suction outlet; (c) an outlet pipe extending from the suction outlet away from the suction chamber housing, said outlet pipe being configured for liquid communication with the suction chamber and being disposed to receive the liquid flow; the outlet pipe defining at least a first inner diameter along a portion of its length and a second inner diameter along another portion of its length, the second inner diameter being less than the first inner diameter; and (d) a suction pipe, a first end of the suction pipe opening into the suction chamber at the suction inlet, and a second end of the suction pipe opening into the surrounding environment; wherein the nozzle assembly extends into the suction chamber towards the suction outlet and into the imaginary line of flow of the suction pipe.
In another embodiment, this invention provides a pumping system comprising: (a) a nozzle assembly which is sized and configured to (i) receive a pressurized liquid and a gas, and (ii) eject the pressurized liquid as a liquid flow while feeding the gas into proximity with the periphery of the liquid flow; (b) a housing defining a suction chamber into which the nozzle assembly may eject the liquid flow, the housing further defining a suction inlet and a suction outlet; (c) an inlet pipe for providing pressurized liquid to the nozzle assembly; (d) a gas conduit for providing the gas to the nozzle assembly; (e) an outlet pipe extending from the suction outlet away from the suction chamber, the outlet pipe being configured for liquid communication with the suction chamber and being disposed to receive the liquid flow; the outlet pipe defining at least a first inner diameter along a portion of its length and a second inner diameter along another portion of its length, the second inner diameter being less than the first inner diameter; and (f) a suction pipe, a first end of the suction pipe opening into the suction chamber at the suction inlet, and a second end of the suction pipe opening into the surrounding environment. This invention also provides a system for dredging matter from the bottom of a body of water, the system comprising: (a) a pumping system as described above in this paragraph, (b) a buoyant platform equipped to raise and lower at least a portion of the pumping system relative to the bottom of the body of water, and (c) a first pump for providing the pressurized liquid to the nozzle assembly.
In yet another embodiment of the present invention, a method of moving, from one location to another, a slurry comprised of a solid and a liquid, is provided. The method comprises:
a. injecting a pressurized liquid into a nozzle assembly to produce a flow of pressurized liquid,
b. providing a gas to the nozzle assembly to surround the flow of pressurized liquid with the gas,
c. directing the flow of pressurized liquid surrounded by the gas into a suction chamber in fluid communication with a suction pipe and an outlet pipe, the outlet pipe defining a venturi-like inner surface, and directing the flow of pressurized liquid surrounded by the gas toward the outlet pipe to produce a vacuum at a free end of the suction pipe, and
d. controlling the flow rate of the gas into said nozzle assembly to thereby control the weight ratio of solid to liquid in the slurry so moved.
These and other embodiments, objects, advantages, and features of this invention will be apparent from the following description, accompanying drawings and appended claims.